Inhomogeneous order-parameter suppression in disordered d-wave superconductors

Abstract

We report on a numerical study of disorder effects in 2D d-wave BCS superconductors. We compare exact numerical solutions of the Bogoliubov-deGennes (BdG) equations for the density of states $ρ(E)$ with the standard T-matrix approximation. Local suppression of the order parameter near impurity sites, which occurs in self-consistent solutions of the BdG equations, leads to apparent power law behavior $ρ(E) \sim |E|^α$ with non-universal $α$ over an energy scale comparable to the single impurity resonance energy $Ω_0$. We show that the novel effects arise from static spatial correlations between the order parameter and the impurity distribution.